Field of Invention
The present invention relates to a composition for pattern formation, a pattern-forming method and a block copolymer.
Description of the Related Art
Miniaturization of various types of electronic device structures such as semiconductor devices and liquid crystal devices has been accompanied by demands for microfabrication of patterns in pattern-forming steps. In these days, although fine patterns having a line width of about 50 nm can be formed using, for example, an ArF excimer laser, further finer pattern formation has been required.
To meet the demands described above, a directed self-assembly pattern forming method which utilizes a phase separation (microdomain) structure constructed through directed self-assembly, as generally referred to, that spontaneously forms an ordered pattern has been proposed. As such a directed self-assembly pattern forming method, a method for forming an ultrafine pattern by directed self-assembly using a block copolymer that is obtained by copolymerizing a monomer compound having a specific property and a monomer compound having a property that differs from the specific property has been known (see Japanese Unexamined Patent Application, Publication No. 2008-149447, Japanese Unexamined Patent Application (Translation of PCT Application), Publication No. 2002-519728, and Japanese Unexamined Patent Application, Publication No. 2003-218383). According to this method, a pattern can be formed in a self-aligning manner by way of a feature that polymer structures having the same property tend to cluster through annealing of a film containing the block copolymer.
However, the pattern obtained by the conventional method described above is not concluded to be sufficiently fine and therefore, various techniques have been studied in regard to the structure of the block copolymer, and for example, introducing a silicon atom into a part of blocks of the block copolymer has been known (see Japanese Unexamined Patent Application, Publication Nos. 2013-528664 and 2013-166932, and ACS Macro Lett., 1, 1279 (2012)). However, although the composition containing such a conventional block copolymer readily forms a directed self-assembling film having a regular array structure with fine pitches, the composition is disadvantageous in that generation of defects of the regular array structure cannot be sufficiently inhibited.